Deduplication of data stored in a data repository may be useful in multiple contexts. In one example, a person may combine multiple contact lists (e.g., an email contact list, a social network contact list, and a mobile phone contact list) and wish to remove duplicate entries. In another example, a team of recruiters may be prohibited (e.g., for legal, company policy or best practice reasons) from contacting candidates that the team has previously contacted during a time period (e.g., in the last six months). Thus, when accessing information about a candidate in a social networking service or a webpage, a recruiter may desire to determine whether information about the applicant (including application about previous times when the candidate was contacted by recruiters) is stored in the teams applicant tracking system (ATS). As the foregoing illustrates, techniques for deduplication of data stored in an ATS and data stored externally to the ATS may be desirable.